Pressure sensor

ABSTRACT

In a pressure sensor including a substrate supported by input-output terminals, the substrate is provided with a circular hole located substantially at its central part, and an arc-shaped communication hole formed adjacent to three through-holes to which three of lead pins are inserted and fixed, respectively.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims priority to U.S. patent application Ser. No.16/289,194, filed Feb. 28, 2019, which claims the benefit of JapanesePatent Application No. 2018-047833, filed Mar. 15, 2018, which arehereby incorporated by reference herein in their entirety.

BACKGROUND OF THE INVENTION Field of the Invention

The present invention relates to a pressure sensor including a substratesupported by input-output terminals.

Description of the Related Art

As disclosed in Japanese Patent No. 5656319, for example, a sensor unitconstituting part of a liquid-sealed semiconductor pressure sensor isprovided in a pressure chamber formed inside a metallic joint memberjoined to a housing (which is referred to as an element body in JapanesePatent No. 5656319) in a cover member. For example, such sensor unitcomprises, as its main components: a diaphragm supported in the jointmember and isolating the above-described pressure chamber from a liquidseal chamber to be described below; the liquid seal chamber formed abovethe diaphragm and storing silicone oil serving as a pressuretransmission medium; a sensor chip provided in the liquid seal chamberand detecting a variation in pressure of the silicone oil which iscaused through the diaphragm; a chip mounting member supporting thesensor chip; and eight lead pins transmitting an output signal from thesensor chip and supplying power to the sensor chip, and so forth. Thelead pins serving as input-output terminals are fixed to inside ofhermetic glass which is formed inside the housing (the element body) andto which the chip mounting member is fixed. There is a case where oneend portion of each lead pin is inserted and fixed to a correspondingone of through-holes in the substrate that is located away upward froman upper end surface of the hermetic glass in order to facilitatesoldering work (see FIG. 1). Hereby, the substrate is supported by theend portions of the lead pins. The other end portion of each lead pinprojecting from a lower end surface of the hermetic glass is connectedto the sensor chip by using a bonding wire. A conductive pattern on theabove-described substrate is electrically connected to external leadlines.

A space inside the cover member defined above the chip mounting memberand the housing (the element body) is filled with an adhesive in such away that the adhesive covers and hermetically seals the substrate, thelead pins, and a part of the external lead lines. Herewith, because theadhesive put therein adheres to an inner peripheral surface of the covermember, the lead pins, the substrate, and an outer peripheral portion ofthe external lead lines, the adhesive prevents moisture such as dewcondensation water and rainwater on surfaces of the adhesive and of theexternal lead lines from penetrating into the cover member from theoutside.

SUMMARY OF THE INVENTION

In the pressure sensor as disclosed in Japanese Patent No. 5656319, whenthe adhesive is charged into a space between a lower surface of thesubstrate and end surfaces of the chip mounting member and of thehousing (the element body) in the cover member, bubbles contained in theadhesive may stick to and remain around the lead pins located below thesubstrate. In this instance, if the adhesive is solidified in the statewhere the bubbles stick to and remain around the lead pins located belowthe substrate, the bubbles around the lead pins may be confined in theadhesive. Hereby, electrostatic strength around the lead pins may bedeteriorated as a consequence of reduction in dielectric strengthbetween the lead pins and the housing because the dielectric strength ofair is inferior to that of the adhesive. Moreover, if the bubbles in theadhesive emerge on its uppermost surface of the adhesive visible fromthe outside during the hardening of the adhesive and the uppermostsurface is hardened in a recessed state, as a consequence, the adhesivemay develop a defect in appearance.

In view of the above-described problem, the present invention aims toprovide a pressure sensor including a substrate supported byinput-output terminals. The present invention can discharge bubblescontained in an adhesive put in a cover member easily from below asubstrate in the cover member into an internal space of a sensor unitaccommodating portion and into outside continuous with the internalspace.

To achieve the above-described object, a pressure sensor according tothe present invention includes: a sensor unit having a sensor chip fordetecting a pressure and transmitting a detection output signal, atleast one input-output terminal electrically coupled to the sensor chip,and a supporting member for supporting the sensor chip; a substratesupported by one end of the input-output terminal and electricallycoupled to the input-output terminal; and a sensor unit accommodatingportion filled with a sealant, for accommodating the substrate and thesensor unit. Wherein, the substrate includes at least one bubbledischarge opening located adjacent to the input-output terminal, to thebubble discharge opening for discharging a bubble into an internal spaceof the sensor unit accommodating portion and into outside beingcontinuous with the internal space when the sensor unit accommodatingportion is filled with the sealant.

Moreover, another pressure sensor according to the present inventionincludes: a sensor unit having a sensor chip for detecting a pressureand transmitting a detection output signal, at least one input-outputterminal electrically coupled to the sensor chip, and a supportingmember for supporting the sensor chip; a connector electrically coupledto the input-output terminal; and a sensor unit accommodating portionfilled with a sealant, for accommodating the connector and the sensorunit. Wherein, the connector includes at least one bubble dischargeopening for discharging a bubble into an internal space of the sensorunit accommodating portion and into outside being continuous with theinternal space when the sensor unit accommodating portion is filled withthe sealant. This pressure sensor may further include a substratesupported by one end of the input-output terminal and electricallycoupled to the input-output terminal, and the substrate may include atleast one bubble discharge opening located adjacent to the input-outputterminal, for discharging the bubble into the internal space of thesensor unit accommodating portion and into the outside being continuouswith the internal space when the sensor unit accommodating portion isfilled with the sealant.

A plurality of bubble discharge openings may be formed between an outerperipheral portion at a lower end of a connection port portion and aninner peripheral portion of a terminal base in the connector atpredetermined intervals along a circumferential direction of theconnection port portion.

The sensor unit may further include a housing having an insulatingmember for supporting the input-output terminal.

The supporting member may be a sensor housing.

The bubble discharge opening may be either a communication hole in thesubstrate or a cutout on the substrate.

The bubble discharge opening may be provided adjacent to a terminal outof the input-output terminals which is solder-fixed to the substrate.The supporting member may be a chip mounting member made of a metal andsupported and insulated from the sensor unit.

According to the pressure sensor of the present invention, the substrateincludes at least one bubble discharge opening located adjacent to theinput-output terminal that is solder-fixed to the substrate anddischarges the bubble into the internal space of the sensor unitaccommodating portion when the sensor unit accommodating portion isfilled with the sealant. This makes it possible to discharge bubblescontained in an adhesive put in a cover member serving as the sensorunit accommodating portion easily from below the substrate in the covermember to the internal space of the sensor unit accommodating portionand to the outside continuous with the internal space.

Further features of the present invention will become apparent from thefollowing description of exemplary embodiments with reference to theattached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plan view showing a substrate to be used in an example of apressure sensor according to the present invention together with leadpins provided thereto;

FIG. 2 is a cross-sectional view showing a configuration of the exampleof the pressure sensor according to the present invention;

FIG. 3 is a cross-sectional view made available for describing a methodof filling with a sealant in the example shown in FIG. 2;

FIG. 4 is a plan view showing another example of the substrate to beused in the example shown in FIG. 2 together with the lead pins providedthereto;

FIG. 5 is a cross-sectional view showing a configuration of anotherexample of a pressure sensor according to the present invention;

FIG. 6 is a partial cross-sectional view showing a connector unitillustrated in FIG. 5, which is taken along the VI-VI line;

FIG. 7 is a cross-sectional view showing a configuration of stillanother example of a pressure sensor according to the present invention;

FIG. 8 is a cross-sectional view showing a configuration of stillanother example of a pressure sensor according to the present invention;and

FIG. 9 is a cross-sectional view showing a configuration of stillanother example of a pressure sensor according to the present invention.

DESCRIPTION OF THE EMBODIMENTS

FIG. 2 schematically illustrates a configuration of an example of apressure sensor according to the present invention.

In FIG. 2, a pressure sensor comprises a joint member 30 to be joined toa piping that guides a fluid to be subjected to detection of a pressure,and a sensor unit accommodating portion connected to a base plate 28 ofthe joint member 30, the sensor unit accommodating portion foraccommodating a sensor unit to be described later and supplying adetection output signal from a sensor chip 16 to a given pressuremeasurement device.

The joint member 30 made of a metal has a female screw portion 30 fsprovided on the inside of the joint member 30 and being screwed into amale screw portion provided at a connector portion of theabove-described piping. The female screw portion 30 fs communicates witha port 30 a of the joint member 30 which guides the fluid supplied froma direction indicated with an arrow P to a pressure chamber 28A to bedescribed later. One of open ends of the port 30 a is open toward thepressure chamber 28A to be formed between the base plate 28 of the jointmember 30 and a diaphragm 32 of the sensor unit.

A contour portion of the sensor unit accommodating portion is formed bya cylindrical waterproof case 20 that serves as a cover member. Anopening 20 b is formed at a lower end portion of the waterproof case 20made of a resin. A peripheral edge of the base plate 28 of the jointmember 30 is engaged with a stepped portion on a peripheral edge of theopening 20 b located inside.

Either air or a liquid being the fluid is supplied into the pressurechamber 28A through the port 30 a of the joint member 30. A lower endsurface of a housing 12 of the sensor unit is placed on the base plate28.

The sensor unit for detecting a pressure inside the pressure chamber 28Aand transmitting the detection output signal comprises, as its maincomponents: the housing 12 in a cylindrical shape; the metal diaphragm32 for isolating the pressure chamber 28A from an inner peripheralportion of the housing 12; the sensor chip 16 having a plurality ofpressure detection elements; a metal chip mounting member 18 forsupporting the sensor chip 16 at one end portion thereof through anadhesive layer; lead pins 24LP1, 24LP2, 24LP3, 24LP4, 24LP5, 24LP6,24LP7, and 24LP8 (see FIG. 1) being electrically coupled to the sensorchip 16 and constituting grouped input-output terminals; and hermeticglass 14 for fixing the grouped input-output terminals and an oil fillerpipe 22 (see FIG. 1) between an outer peripheral surface of the chipmounting member 18 and an inner peripheral surface of the housing 12.

Note that FIG. 2 representatively illustrates only the lead pin 24LP7out of the lead pins 24LP1 to 24LP8, and does not illustrate the oilfiller pipe. An outer peripheral edge of the diaphragm 32 is supportedby one of lower end surfaces of the housing 12 opposed to theaforementioned pressure chamber 28A. A diaphragm protection cover 34 toprotect the diaphragm 32 provided in the pressure chamber 28A isprovided with a plurality of communication holes. A peripheral edge ofthe diaphragm protection cover 34 is joined by welding to the lower endsurface of the housing 12, which is made of stainless steel, togetherwith the outer peripheral edge of the diaphragm 32.

A liquid seal chamber 13 formed between the sensor chip 16 opposed tothe metallic diaphragm 32 and an end surface of the hermetic glass 14 isfilled, for example, with a predetermined amount of silicone oil or afluorine-based inert liquid serving as a pressure transmission medium PMthrough the oil filler pipe 22. Note that one of end portions of the oilfiller pipe 22 is crushed and occluded after the filling with the oil.

An electric potential adjustment member 17 made of a metal is furthersupported on the lower end surface of the hermetic glass 14 between thediaphragm 32 and the sensor chip 16 which is provided in a recess formedat an end portion of the hermetic glass 14 that serves as an insulatingmember. The electric potential adjustment member 17 having acommunication hole is coupled to a terminal connected to zero potentialof a circuit of the sensor chip 16 as disclosed in Japanese Patent No.3987386, for example.

Note that the insulating member to fix the grouped input-outputterminals and the oil filler pipe 22 (see FIG. 1) between the outerperipheral surface of the chip mounting member 18 and the innerperipheral surface of the housing 12 is not limited to theabove-described example. For instance, a ceramic, a heat resistant resinor the like that secures the airtightness of the liquid seal chamber 13while establishing insulation of the grouped input-output terminals andthe like may be used instead.

The lead pin 24LP6 and the lead pin 24LP7 are used as two power supplyterminals (Vcc, GND), for example. The lead pin 24LP8 is used as atransmission terminal (Vout) for the output signal from the sensor chip16, for example. The lead pins 24LP1 to 24LP5 are used as fiveadjustment terminals, respectively. Both end portions of each of thelead pins 24LP1 to 24LP5 project toward the above-described recessformed at the end portion of the hermetic glass 14 and a correspondingone of through-holes 10 ai (i=1 to 8) in a substrate 10 to be describedlater. Note that the number of the lead pins is not limited to thisexample and may be set as appropriate according to the number ofinput-output ports of the sensor chip 16, for instance.

Both end portions of each of the lead pin 24LP6, the lead pin 24LP7, andthe lead pin 24LP8 project toward the above-described recess formed atthe end portion of the hermetic glass 14 and a corresponding one of thethrough-holes 10 ai (i=1 to 8) in the substrate 10 to be describedlater. At that time, the end portions of the lead pin 24LP6, the leadpin 24LP7, and the lead pin 24LP8 inserted into the correspondingthrough-holes 10 ai in the substrate 10 are solder-fixed to peripheraledge of each through-hole 10 ai in the substrate 10, respectively.

As shown in FIG. 1, for example, the substrate 10 is formed into a discshape and is provided with a circular hole 10 d located substantially ata central portion as a first bubble discharge opening. Moreover, thesubstrate 10 has the through-holes 10 ai, and a through-hole 10 b intowhich the oil filler pipe 22 is inserted. Predetermined circumferentialequally spaced apart above-described lead pins 24LP1 to 24LP8 areinserted into the through-holes 10 ai each with a given gap around thehole 10 d. The predetermined equally spacing is set at 40° spacing, forinstance.

Moreover, an arc-shaped communication hole 10 c serving as a secondbubble discharge opening is formed adjacent to the three through-holes10 ai into which the lead pin 24LP6, the lead pin 24LP7, and the leadpin 24LP8 are inserted, respectively. The arc of the communication hole10 c has a predetermined center angle α. The center angle α is set at90°, for example. As shown in FIG. 2, a conductive pattern on thesubstrate 10 is formed in an area from the through-holes 10 ai intowhich the lead pins 24LP6 to 24LP8 are inserted and solder-fixed to aposition where a core wire 38 a of a lead line 38 is connected to thesubstrate. The lead line 38 is connected to the given pressuremeasurement device (not shown). While the shape of the substrate 10 isformed into the circular shape, the present invention is not limitedonly to this example and the shape of the substrate 10 may be formedinto a polygonal shape, for instance.

Herein, the sensor chip 16 is adapted to use one provided with adiaphragm portion inside such as in a piezoresistive effect system. Thesensor chip 16 adopting a piezoresistive effect mainly comprises asemiconductor substrate unit which is provided with a diaphragm portionmade of a material (such as single crystal silicon) that has thepiezoresistive effect, and a mount made of glass or the like. Thesemiconductor substrate unit and the mount are bonded to each other byanodic bonding or the like, and a space between the diaphragm portion ofthe semiconductor substrate unit and the mount forms a referencepressure chamber. The diaphragm portion of the semiconductor substrateunit is provided with semiconductor strain gauges and a bridge circuitis formed by bridge-connecting these semiconductor strain gauges. Adeformation of the diaphragm portion caused by a difference between anoutside air pressure and the pressure in the reference pressure chamberis taken in the form of an electric signal representing a change ingauge resistance among the semiconductor strain gauges by this bridgecircuit. As a consequence, a pressure of the fluid is detected by thebridge circuit. As shown in FIG. 2, the sensor chip 16 and the lead pins24LP1 to 24LP8 are connected to one another by using bonding wires Wi.

Moreover, an internal space surrounded by an inner peripheral surface 20a of the waterproof case 20, the housing 12, and an upper end surface ofthe hermetic glass 14 is filled with a predetermined amount of a sealant26. The sealant 26 comprises an addition reaction type adhesive such asa urethane-based adhesive or an epoxy-based adhesive, for example.

In the above-described configuration, when the sensor unit is arrangedin the waterproof case 20 and the core wire 38 a of the lead line 38 isconnected to the substrate 10, and then the sealant 26 is put into thewaterproof case 20 in a direction indicated with arrows in FIG. 3, forexample, even if bubbles Ai are taken in the sealant 26 that is put intoa gap between the upper end surface of the housing 12, the hermeticglass 14 and a lower surface of the substrate 10, the bubbles Ai arepushed out by the sealant 26 to the internal space located above throughthe hole 10 d in the substrate 10 without remaining in the space, andare easily pushed out and discharged to the internal space locatedthereabove through the communication hole 10 c. Hence, no bubbles Aiwill remain in the sealant 26 when the sealant 26 is solidified, thuspreventing a situation where the undesired bubbles Ai that may bringabout the deterioration in electrostatic strength are confined in thesealant 26 near the lead pin 24LP6, the lead pin 24LP7, and the lead pin24LP8.

Note that the bubble discharge openings in the substrate 10 are notlimited to the aforementioned examples. Such an opening may be a cutout40 c as shown in FIG. 4, for instance. Components in FIG. 4 identical tothe components shown in FIG. 1 will be denoted by identical referencenumerals and overlapping explanations thereof will be omitted.

In FIG. 4, a substrate 40 is formed into a disc shape, for example. Thesubstrate 40 includes through-holes 40 ai (i=1 to 8) into whichpredetermined circumferential equally spaced apart above-described leadpins 24LP1 to 24LP8 are inserted each with a given gap, and athrough-hole 40 b into which the oil filler pipe 22 is inserted.Moreover, the cutout 40 c in a fan-shape serving as the bubble dischargeopening is formed adjacent to three of the through-holes 40 ai intowhich the lead pin 24LP6, the lead pin 24LP7, and the lead pin 24LP8 areinserted, respectively. The arc of the cutout 40 c has a prescribedcenter angle β. The center angle β is set at about 90°, for example. Aconductive pattern on the substrate 40 is formed in an area from thethrough-holes 40 ai into which the lead pins 24LP6 to 24LP8 are insertedand solder-fixed to the position where the core wire 38 a of the leadline 38 is connected to the substrate. While the substrate 40 is shapedlike the circular shape, the shape of the substrate is not limited onlyto this example and the substrate 40 may be shaped like a polygonalshape, for instance. In addition, while the cutout 40 c is shaped likethe arc shape, the shape of the cutout is not limited only to thisexample and the cutout 40 c may be shaped like any of a rectangularcutout provided at least one position, a cutout having a partial cut-offV-shape or D shape, and the like. The lead line 38 is connected to thegiven pressure measurement device (not shown).

Note that the cutout 40 c is formed at the same distance away from thethree through-holes 40 ai into which the solder-fixed lead pins 24LP6,24LP7, and 24LP8 are inserted, respectively. However, the presentinvention is not limited only to this example. For instance, the cutout40 c may be formed away from the three through holes 40 ai at differentdistances from one another.

In the above-described configuration, when the sensor unit is arrangedin the waterproof case 20 and the core wire 38 a of the lead line 38 isconnected to the substrate 40, and then the sealant 26 is put into thewaterproof case 20, even if the bubbles are taken in the sealant 26 thatis put into the gap between the upper end surface of the housing 12, thehermetic glass 14 and a lower surface of the substrate 40, the bubblesare passed through the cutout 40 c on the substrate 40 without remainingin the space and are easily pushed out by the sealant 26 and dischargedto the internal space located thereabove. Hence, no bubbles Ai willremain in the sealant 26 when the sealant 26 is solidified, thuspreventing the situation where the undesired bubbles Ai that may bringabout the deterioration in electrostatic strength are confined in thesealant 26 near the lead pin 24LP6, the lead pin 24LP7, and the lead pin24LP8.

Note that each of the hole 10 d, the communication hole 10 c, and thecutout 40 c is provided at one position in the substrate 10 or thesubstrate 40 in the above-described examples. However, the presentinvention is not limited only to these examples and the communicationholes 10 c or the cutouts 40 c may be provided at two or more positions,for instance. Further, the bubble discharge opening may be a combinationof the hole 10 d, the communication hole 10 c, and/or the cutout 40 c asappropriate.

FIG. 5 schematically shows a configuration of another example of apressure sensor according to the present invention. Note that componentsin FIG. 5 identical to the components shown in the example illustratedin FIG. 2 will be denoted by identical reference numerals andoverlapping explanations thereof will be omitted.

In the example shown in FIG. 2, the lead line 38 to be connected to theconductive pattern on the substrate 10 is directly coupled to the givenpressure measurement device (not shown). On the other hand, in theexample shown in FIG. 5, a lead line Le to be connected to theconductive pattern on the substrate 10 is coupled to the pressuremeasurement device (not shown) through a connector 52. Note that as withthe example show in FIG. 1, the substrate 10 has the through-holes 10 ai(i=1 to 8) and the through-hole 10 b which are located at the positionscorresponding to the lead pins 24LP1 to 24LP8 and the oil filler pipe22, respectively, and moreover, the hole 10 d and the communication hole10 c serving as the bubble discharge openings. The through-holes 10 aias well as the through-hole 10 b, the hole 10 d, and the communicationhole 10 c are arranged at predetermined intervals, respectively.

In FIG. 5, the pressure sensor comprises the joint member 30 to beconnected to the piping that guides the fluid to be subjected todetection of a pressure, and the sensor unit accommodating portionconnected to the base plate 28 of the joint member 30, the sensor unitaccommodating portion for accommodating the sensor unit and supplyingthe detection output signal from the sensor chip 16 to the givenpressure measurement device. The contour portion of the sensor unitaccommodating portion is formed by a cylindrical waterproof case 50serving as a cover member. An opening 50 b is formed at a lower endportion of the waterproof case 50 made of a resin. The peripheral edgeof the base plate 28 of the joint member 30 is engaged with a steppedportion on a peripheral edge of the opening 50 b located inside.

In addition, the female connector 52 to be fitted with an outerperipheral portion of the housing 12 is molded by using a resinmaterial. The female connector 52 comprises a connection port portion52FC which is attachable to and detachable from a male connector (notshown), and a terminal base 52B formed integrally with a base part ofthe connection port portion 52FC, the terminal base for supportingconnection terminals 54 ai (i=1 to 3). A lower part of the terminal base52B having a stepped cylindrical shape is fitted with the outerperipheral portion of the housing 12. The substrate 10, the lead pins24LP1 to 24LP8, and the oil filler pipe 22 which are described above arearranged at a central part inside the terminal base 52B. The conductivepattern on the substrate 10 is connected to the connection terminals 54ai (i=1 to 3) through the lead line Le. Herein, although the connector52 is provided by forming the connection port portion 52FC integrallywith the terminal base 52B, the connector is not limited to this exampleand the connection port portion 52FC and the terminal base 52B may beformed separately from each other and then assembled together.

The connection terminals 54 ai are supported by a terminal supportportion 52FCE formed inside of a lower end of the connection portportion 52FC having the stepped cylindrical shape. Each connectionterminal 54 ai is supported in such a way as to be parallel to thecenter axis of the connection port portion 52FC. As shown in FIG. 6, anopening 52 a serving as a first bubble discharge opening is formedbetween an inner peripheral portion of the connection port portion 52FCand the terminal support portion 52FCE.

Moreover, a communication hole 52 b serving as a second bubble dischargeopening, a communication hole 52 c serving as a third bubble dischargeopening, a communication hole 52 d serving as a fourth bubble dischargeopening, and a communication hole 52 e serving as a fifth bubbledischarge opening are formed between an outer peripheral portion at alower end of the connection port portion 52FC and a cylindrical portionof the terminal base 52B, equally spaced apart at about 90° along acircumferential direction of the connection port portion 52FC.

A space between an inner peripheral surface 50 a of the waterproof case50 and an outer peripheral portion at a lower part of the connectionport portion 52FC and the terminal base 52B of the connector 52, and aninternal space surrounded by an inner peripheral surface of the terminalbase 52B and the upper end surface of the hermetic glass 14 as well asthe housing 12 are filled with a predetermined amount of the sealant 26.Hereby, the opening 52 a, and the communication holes 52 b to 52 e arealso filled with the sealant 26.

In the above-described configuration, when the sensor unit is arrangedin the waterproof case 50 and the lead line Le is connected to thesubstrate 10 as well as the connection terminals 54 ai and then thesealant 26 is put into the waterproof case 50, even if bubbles are takenin the sealant 26 that is put into the inside of the terminal base 52B,the bubbles are easily pushed out and discharged to the internal spacelocated thereabove through the opening 52 a and the communication holes52 b to 52 e without remaining in the sealant 26. Accordingly, it ispossible to keep the bubbles from remaining and causing depressions onthe surface of the sealant 26 in the case of solidification of thesealant 26. Thus, the sealant 26 can be kept from being solidified withits surface in the recessed state.

Moreover, as a consequence of using the substrate 10, when the sealant26 is put into the waterproof case 50, the bubbles Ai do not remain inthe sealant and are discharged to the internal space located thereabovethrough the hole 10 d and the communication hole 10 c in the substrate10. Hence, when the sealant 26 is hardened, the undesired bubbles Aithat may bring about the deterioration in electrostatic strength arekept from being confined in the sealant 26 near the lead pins 24LP1 to24LP8.

FIG. 7 schematically shows a configuration of still another example of apressure sensor according to the present invention. The example shown inFIG. 2 has the configuration in which the metallic electric potentialadjustment member 17 is supported on the lower end surface of thehermetic glass 14. Instead, in the example shown in FIG. 7, a shieldmember 15 serving as an electric field shielding member is providedbetween one of end surfaces of the sensor chip 16 and the diaphragm 32in the liquid seal chamber 13. The shield member 15 in a cap shape isdesigned to shield an undesired electric field applicable to a signalprocessing electronic circuit unit in the sensor chip 16.

Note that components in FIG. 7 identical to the components shown in theexample illustrated in FIG. 2 will be denoted by identical referencenumerals and overlapping explanations thereof will be omitted.

The shield member 15 may be made from a conductive metal material suchas stainless steel, copper, and aluminum. Alternatively, the shieldmember 15 may be made from an insulating material such as a resin,glass, and a ceramic and then integrated with a surface layer of aconductive metal deposited by adhesion, vapor deposition, sputtering,plating, and the like.

Four fixation end portions of the shield member 15 are brought close toan outer peripheral portion of the sensor chip 16 on one of end surfacesof a disc-shaped conductive plate 19, and are joined to and electricallycoupled thereto. Although illustration is omitted, a plurality ofopenings are provided in a side surface of the shield member 15. Theshape of the shield member 15 is formed into a shape that enablesmovement of the pressure transmission medium PM such that a pressurecorresponding to a displacement of the diaphragm 32 is transmitted tothe sensor chip 16 through the pressure transmission medium PM.

The conductive plate 19 is connected and electrically coupled to atleast one of the lead pins 24LP1 to 24LP8, such as a zero (V) terminalthrough the bonding wire Wi. In this configuration, electric potentialsat the shield member 15 and the conductive plate 19 are set equal to anelectric potential in an electronic circuit mounted on the sensor chip16.

A portion of the shield member 15 that covers the entire sensor chip 16is provided with a prescribed clearance between the end surface of thesensor chip 16 and the portion of the shield member. Note that anexternal length of the shield member 15 may be set as appropriateaccording to the size of the signal processing electronic circuit unitof the sensor chip 16 so as to shield the undesired electric fieldapplicable to the signal processing electronic circuit unit of thesensor chip 16.

Accordingly, by arranging the shield member 15 having the same electricpotential as the electric potential of the sensor chip 16 between thediaphragm 32 and the signal processing electronic circuit unit of thesensor chip 16, the electric field to be applied to the sensor chip 16,which is generated by a difference in potential between a controlcircuit (not shown) side and the diaphragm 32 having the same electricpotential as that of a primary power source (not shown) of the unit, isshielded by the shield member 15. In addition, because the shield member15 and the sensor chip 16 have the same electric potential, no electricfield is generated therebetween. For this reason, because the differencein potential that occurs between the sensor chip 16 and the diaphragm 32is not applied to the sensor chip 16, it is possible to prevent theelectronic circuit in the sensor chip 16 from being affected.

FIG. 8 schematically shows a configuration of still another example of apressure sensor according to the present invention. The pressure sensorshown in FIG. 8 comprises the joint member 30 to be joined to the pipingthat guides the fluid to be subjected to detection of a pressure, and ametal sensor housing 58 in which the joint member 30 is connected to thebase plate 28 by brazed joint or the like, the sensor housing 58 foraccommodating the sensor unit.

Note that components in FIG. 8 identical to the components shown in theexample illustrated in FIG. 2 will be denoted by identical referencenumerals and overlapping explanations thereof will be omitted.

The sensor unit for detecting a pressure inside the pressure chamber 28Aand transmitting the detection output signal comprises, as its maincomponents: the metal diaphragm 32 for isolating the pressure chamber28A from an inner peripheral portion of the sensor housing 58; a sensorchip 66 provided with a plurality of pressure detection elements and thesignal processing electronic circuit unit for processing signals fromthe pressure detection elements; and grouped input-output terminals 64ai (i=1 to 8) electrically coupled to the sensor chip 66.

The pressure transmission medium PM is put in through a hole 58 a in thesensor housing 58 and then the hole 58 a is occluded by a plug member56. The grouped input-output terminals 64 ai are supported by beinginsulated from the sensor housing 58 through hermetic glass 65. Thesensor chip 66 is cemented to an inner peripheral surface of the sensorhousing 58. The grouped input-output terminals 64 ai and the sensor chip66 are connected to one another by using the bonding wires Wi.

Two of the grouped input-output terminals 64 ai are used as power supplyterminals (Vcc, GND), for example, and another one of the groupedinput-output terminals 64 ai is used as a transmission terminal (Vout)for the output signal from the sensor chip 66, for example. The rest ofthe terminals are used as the five adjustment terminals, respectively.Both end portions of each input-output terminal project toward an endportion of the hermetic glass 65 on an inner peripheral surface of theabove-described sensor housing 58, and to the corresponding one of thethrough-holes 10 ai (i=1 to 8) in the substrate 10, respectively.

FIG. 9 schematically shows a configuration of still another example of apressure sensor according to the present invention. The pressure sensorshown in FIG. 9 comprises the joint member 30 to be joined to the pipingthat guides the fluid to be subjected to detection of a pressure, and asensor housing 60 in which the joint member 30 is connected to the baseplate 28 by brazed joint or the like, the sensor housing foraccommodating the sensor unit. The sensor housing 60 is an insulatingmember made of a material such as a ceramic that maintains pressureresistance and airtightness.

Note that components in FIG. 9 identical to the components shown in theexample illustrated in FIG. 2 will be denoted by identical referencenumerals and overlapping explanations thereof will be omitted.

The sensor unit for detecting a pressure inside the pressure chamber 28Aand transmitting the detection output signal comprises, as its maincomponents: the metal diaphragm 32 for isolating the pressure chamber28A from an inner peripheral portion of the sensor housing 60; thesensor chip 66 provided with a plurality of pressure detection elementsand the signal processing electronic circuit unit for processing thesignals from the pressure detection elements; and the groupedinput-output terminals 64 ai (i=1 to 8) electrically coupled to thesensor chip 66.

The pressure transmission medium PM is put in through a hole 60 a in thesensor housing 60 and then the hole 60 a is occluded by the plug member56. The input-output terminals constituting the grouped input-outputterminals 64 ai are inserted into and supported by corresponding holesin the sensor housing 60, respectively. The sensor chip 66 is cementedto an inner peripheral surface of the sensor housing 60. The groupedinput-output terminals 64 ai and the sensor chip 66 are connected to oneanother by using the bonding wires Wi.

Two of the grouped input-output terminals 64 ai are used as the powersupply terminals (Vcc, GND), for example, and another one of the groupedinput-output terminals 64 ai is used as the transmission terminal (Vout)for the output signal from the sensor chip 66, for example. The rest ofthe terminals are used as the five adjustment terminals, respectively.Both end portions of each input-output terminals project toward an endportion of an inner peripheral surface of the above-described sensorhousing 60 and to the corresponding one of the through-holes 10 ai (i=1to 8) in the substrate 10, respectively.

While the present invention has been described with reference toexemplary embodiments, it is to be understood that the invention is notlimited to the disclosed exemplary embodiments. The scope of thefollowing claims is to be accorded the broadest interpretation so as toencompass all such modifications and equivalent structures andfunctions.

What is claimed is:
 1. A pressure sensor comprising: a sensor unitincluding: a sensor chip for detecting a pressure and transmitting adetection output signal, at least one input-output terminal electricallycoupled to the sensor chip, and a supporting member for supporting thesensor chip; a connector electrically coupled to the input-outputterminal; and a sensor unit accommodating portion filled with a sealant,for accommodating the connector and the sensor unit, wherein theconnector includes at least one bubble discharge opening for pushing outand discharging a bubble into an internal space of the sensor unitaccommodating portion and into outside being continuous with theinternal space when the sensor unit accommodating portion is filled withthe sealant.
 2. The pressure sensor according to claim 1, furthercomprising: a substrate supported by one end of the input-outputterminal and electrically coupled to the connector, wherein thesubstrate includes at least one bubble discharge opening extendingthrough the substrate in a first direction and separated from theinput-output terminal in a second direction traverse to the firstdirection by the substrate, the bubble discharge opening for pushing outand discharging a bubble on a first side of the substrate into a portionof the internal space of the sensor unit accommodating portion on asecond side of the substrate, wherein the bubble is pushed out anddischarged outside of the sensor unit accommodating portion when thesensor unit accommodating portion is filled with the sealant, whereinthe at least one bubble discharge opening is filled with the sealantafter filling the sensor unit accommodating portion with the sealant. 3.The pressure sensor according to claim 1, wherein a plurality of thebubble discharge openings are formed between an outer peripheral portionat a lower end of a connection port portion and an inner peripheralportion of a terminal base in the connector at predetermined intervalsalong a circumferential direction of the connection port portion.
 4. Thepressure sensor according to claim 1, wherein the sensor unit furthercomprises a housing including an insulating member for supporting theinput-output terminal.
 5. The pressure sensor according to claim 2,wherein the bubble discharge opening is a communication hole in thesubstrate.
 6. The pressure sensor according to claim 2, wherein thebubble discharge opening is a cutout on the substrate.
 7. The pressuresensor according to claim 2, wherein the bubble discharge opening isprovided adjacent to one of a plurality of the input-output terminalswhich is solder-fixed to the substrate.
 8. The pressure sensor accordingto claim 1, wherein the supporting member is a chip mounting member madeof a metal and supported and insulated from the sensor unit.